Several soluble peroxidase isoenzymes are expressed in a landrace of Vigna sp. cultivated in the north of Cameroon (landrace called Vn in previous study) during seed germination. There are at least two cathodic peroxidases and eight major anodic peroxidases as shown by their electrophoretic migration at pH 7.4 under native conditions. These isoperoxidases are more expressed in roots than in shoots. They have different thermal stability, so that heat inactivation kinetics of crude peroxidase extracts from roots do not fit the first-order model. The slow and intermediate migrating groups of anodic isoperoxidases retains a substantial activity after ten minutes of incubation at 80°C and 85°C. An anodic isoperoxidase (named A6 in this study) shows in addition to this great thermal stability, a high activity in seedlings and is expressed both in roots and shoots. The combination of those characteristics makes this isoperoxidase a potential candidate for biotechnological applications. Three major anodic isoperoxidases, of which A6 and another thermostable isoperoxidase, were successfully separated from each other by ion exchange chromatography on DEAE-cellulose, after precipitation of total proteins by ice-cold acetone. This offers the prospect of being able to characterize these isoperoxidases individually in future studies.

Background: Antiretroviral therapies (ART) have been reported to have renal toxicity. However, there is a lack of data on the toxicity of ART in sub-Saharan countries, especially in Cameroon. More studies on their contribution to renal dysfunction in natives from this region are required.Methods: HIV/AIDS patients undergoing eleven different first-line ART at two hospitals in Yaoundé, Cameroon, were selected in this study. Retrospective and prospective data of serum urea and creatinine were collected, and the estimated Glomerular Filtration Rate (eGFR) was calculated. Wilcoxon signed-rank test, paired t-test and chi-square test were used for statistical analysis. The level of significance was set at p < 0.05.Results: Out of 187 participants, there were 134 women (71.66%). The age ranged from 24 to 77 years, with a mean age of 42.47 ± 10.68. The mean serum urea level increased after ART initiation for D4T40 + 3TC + NVP (p = 0.011) and TNF + 3TC + EFV + INH (p = 0.03) regimen in women and for TNF + 3TC + EFV + CTM (p = 0.03) in men. It decreased for D4T40 + 3TC + NVP (p = 0.03) in men. The mean serum creatinine increased for women following regimen AZT + TNF + NVP (p = 0.022) and D4T40 + 3TC + NVP (p = 0.028), and for men on AZT + TNF + NVP (p = 0.03). There was rather a decrease in blood creatinine for women on AZT + 3TC + NVP regimen (p = 0.0032). Mean eGFR decreased for patients on AZT + TNF + NVP (p = 0.015), D4T40 + 3TC + NVP (p = 0.016) and TNF + 3TC + EFV + INH (p = 0.03) regimen. The eGFR dropped below the threshold of 60 ml/ min/1.73 m 2 , for 5/12 patients on D4T40 + 3TC + NVP, 2/6 patients on TNF + 3TC + EFV + INH, 1/4 patients on TNF + 3TC, 6/74 patients on TNF + 3TC + EFV and 1/28 patients on TNF + 3TC + EFV + CTM regimen. However, a significant increase of the eGFR has been observed for treatments with AZT + 3TC + NVP (p = 0.0001), 3TC + TNF + EMB (p = 0.032) and D4T30 + 3TC + EFV (p = 0.032) regimen. Conclusion:Antiviral therapy with stavudine 40 mg (D4T40) or tenofovir-based regimen could lead to renal toxicity. However, the results show that D4T30 + 3TC + EFV, 3TC + TNF + EMB or AZT + 3TC + NVP combinations would be rather protective for renal function, andshould be recommended.

Background: Some applications of peroxidases imply reactions proceeding at high temperatures. In our previous studies, thermostable peroxidase isoenzymes were detected in the seedlings of Vigna sp. One of these isoperoxidases (named peroxidase A6) especially had a great activity in these seedlings. Its isolation and characterization is thus necessary for a thorough study of its biotechnological potential. Results: Peroxidase A6 was purified from Bambara groundnut seedling roots by a combination of gel filtration on Sephadex G-100, heat treatment, CM-cellulose chromatography and DEAE-cellulose chromatography. It has a molecular weight of about 41 kDa and exhibits a great activity toward the oxidation of O-dianisidine, ABTS, TMB, DAB and OPD at acid optimum pH (pH 3 for ABTS, pH 4 for OPD and pH 6 for the others) and toward the reduction of H2O2. Apparent Km values for these substrates were respectively 3.50 mM, 0.12 mM, 1.81 mM, 0.05 mM, 17.22 mM and 2.53 mM; catalytic efficiencies were 5.12×104 mM-1.min-1, 2.22×106 mM-1.min-1, 1.59×105 mM-1.min-1, 1.82×105 mM-1.min-1, 3.17×105 mM-1.min-1and 1.79×106 mM-1.min-1. It has an optimum temperature of activity around 60°C, and its heat inactivation fit to the first-order kinetics, with half-lives of 3.06 weeks, 13.5 hours, 15 min and 3.5 min at 50°C, 70°C, 80°C and 90°C respectively. The calculated activation energy (E) for its thermal inactivation was found to be 221.5 KJ/mol at pH 8. It loose only 5% of its initial activity over a period of 4 months. Mg2+ inhibits the activity of the enzyme. The Ca2+ions greatly increase the stability of this peroxidase at 80 °C, while Mn2+and Zn2+ reduce it. The enzyme is inhibited by sodium azide at concentrations above 1 µM with an IC50value around 10 µM. This inhibition, in addition to the RZ value (A403nm/A280nm) evaluated at 2.4 confirms the presence at its active site of a heme group common to class III peroxidases. Conclusion: The unusual catalytic and thermal characteristics of peroxidase A6 could make it a potent tool in several biotechnological applications, especially as part of kit for enzyme immunoassays and clinical diagnosis.

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Several soluble peroxidase isoenzymes are expressed in a landrace of Vigna sp cultivated in the north of Cameroon (landrace called Vn in previous study) during seed germination. There are at least two cathodic peroxidases and eight major anodic peroxidases as shown by their electrophoretic migration at pH 7.4 under native conditions. These isoperoxidases are more expressed in radicles than in shoots. They have different thermal stability, so that heat inactivation kinetics of crude peroxidase extracts from radicles does not fit the first-order model. One major anodic isoperoxidase of the slow migrating group and at least two others anodic isoperoxidases of the The slow and intermediate migrating groups of anodic isoperoxidasesanodic isoperoxidases are stable for ten minutes of incubation at 80°C and 85°C. The major anodic isoperoxidase of the The less anodic slow migrating groupisoperoxidase (named A6 in this study) shows in addition to this great thermal stability, a high activity during germination and is expressed both in radicles and shoots in large amounts. The combination of those characteristics makes thisthat isoperoxidase a a potential candidate for biotechnological applications.